Cambodia has informed the United States that it is canceling an annual joint military exercise this year, even though planning for the event had already begun.

Defense Ministry spokesman Gen. Chhum Socheath said Monday the Angkor Sentinel exercise had to be postponed because Cambodian forces would be unable to fully participate as a result of two important events: local elections in June and a six-month campaign to eradicate drug-related crime.

U.S. Embassy spokesman Jay Raman confirmed in an e-mail that the exercises for 2017 and 2018 have been canceled. He said military exchanges and training programs are not affected.

Southeast Asian nations, even traditional allies of the United States such as the Philippines, have recently drawn closer to China as Beijing flexes its diplomatic and military muscle in the region.